Responding under schedules combining response-dependent and response-independent shock delivery.
Response-contingent consequences keep behavior strong; non-contingent ones weaken it even when overall rates stay the same.
01Research in Context
What this study did
The researchers mixed response-dependent and response-independent shocks inside one schedule. They kept the total shock rate the same but changed how many shocks depended on the rat’s lever press.
Rats worked on a variable-interval 5-min schedule. Some shocks came only after a press. Others came free, with no response needed.
What they found
As the share of contingent shocks dropped, lever pressing fell. When most shocks were free, the rats slowed down even though the overall pain stayed flat.
Contingency, not just shock frequency, controlled the response rate.
How this fits with other research
Greene et al. (1978) ran a similar test using fixed-interval versus fixed-time shocks. They also saw higher rates when shocks depended on the response. Together, the two 1978 papers show the rule holds across schedule types.
SHETTLEWORTCHARNEY et al. (1965) first showed that contingent shock suppresses key pecks faster than non-contingent shock. Bacotti (1978) extends that idea by smoothly blending the two within one schedule, proving the effect is gradual and orderly.
Kuroda et al. (2013) flipped the valence: they mixed response-dependent and independent food. Response rates rose as the dependent share rose. The same contingency principle works for both punishment and reinforcement.
Why it matters
You may never use shock, but you often mix contingent and non-contingent events. Think of token boards, attention, or escape. If the learner can’t tell which responses produce the consequence, motivation drops. Keep the contingency clear and high. When you thin reinforcement, guard against accidental freebies that weaken the response-reinforcer link.
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02At a glance
03Original abstract
Lever pressing of three squirrel monkeys with experience under continuous avoidance schedules was maintained by response-produced shock under a 5-minute variable-interval schedule. Responding decreased when half of the scheduled shocks were delivered independently of lever pressing and decreased further when all shocks were independent of lever pressing. Responding was lowest when all shocks were eliminated. When the proportion of response-dependent shocks increased, responding increased. This relation occurred even though the frequency and temporal distribution of shock delivery remained the same. Responding of two monkeys increased in a graded fashion as the frequency of shock was increased by arranging variable-time 5-minute, 2-minute, and 1-minute schedules jointly with the variable-interval 5-minute schedule. Thus, increasing the proportion of response-independent shocks decreased responding when the overall frequency of shocks stayed the same, but increased responding when the overall frequency of shock delivery increased.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.29-267